The invention relates generally to gas operating system components for semi-automatic and automatic firearms. Many people own own firearms for various purposes including, but not limited to, protection, trade, hunting, recreation, collecting, and sporting.
Semi-automatic and automatic firearms offer a number of benefits over manually operated firearms. Semi-automatic and automatic firearms generally permit an operator to fire rounds more rapidly than do manually operated firearms. Semi-automatic firearms also generally impart a less harsh recoil impulse to an operator.
A variety of operating systems are employed by semi-automatic and automatic firearms including, but not limited to, blow-back, piston, and direct impingement. A blow-back operating system is generally used on lower pressure cartridges. Piston and direct-impingement operating systems are generally used on higher pressure cartridges. Piston and direct-impingement operating systems are generally used on locking bolt firearms. Piston and direct-impingement operating systems generally rely on a hole, called a gas port, between the chamber and the muzzle of the barrel. When the firearm is fired, a primer ignites powder in the cartridge generating gas. The expanding gas causes pressure to increase forcing the bullet to leave the cartridge and travel down the barrel. Once the bullet passes the port, some of the gas flows out the gas port activating the operating system.
Many direct-impingement operating systems are not user-adjustable. These operating systems rely on allowing sufficient gas to enter the operating system to allow cartridges within a particular band of pressures to successfully activate the operating system. This results in the operating system commonly having excessive operating force under certain conditions causing greater than necessary perceived recoil and equipment wear. This can also result in the operating system having insufficient operating force and not reliably functioning in certain other conditions.
An optimally adjusted operating system allows an appropriate range of loads (bullet weight, velocity, and powders) to cycle the firearm. It also minimizes, or eliminates, excessive energy transferred into the operating system thereby reducing wear on the firearm and perceived recoil to the operator. The amount of gas required to operate the operating system of a firearm can vary based on a number of factors. Installing a suppressor on a firearm generally increases the amount of gas sent through the operating system of a firearm so a previously optimally tuned firearm is likely to be “over-gassed.” Shooting slower ammunition (e.g. subsonic) ammunition can send less gas through the operating system so a previously optimally tuned firearm is likely to be “under-gassed.”
Some user-adjustable piston operating systems comprise an indexed multi-position mechanism. These allow the user to adjust the amount of gas directed into the operating system and permit it to operate successfully with a wider range of ammunition. Many user-adjustable operating systems can become difficult, or impossible, to adjust if they become excessively fouled. Fouling can occur when carbon or other materials in the gas are deposited in the operating system.